1. Technical Field
The present disclosure is directed to a method of determining a plurality of pressures to apply to a wafer during a chemical mechanical polish based on a curvature induced by a film formed on the wafer.
2. Description of the Related Art
The CMP process applies chemical and mechanical forces to the surface of the wafer to prepare a smooth surface for further processing. Pressure is applied to a back of the wafer in a CMP machine to bring the surface of the wafer into contact with a pad and slurry, which are selected to remove a specific film formed on the wafer. In conventional CMP processes, pad and slurry selection, process parameter optimization, and endpoint selection and recipe optimization are widely used methods for improving the post CMP film uniformity and defect. All of these methods have a common point of view, which is based on the type of material being etched. For example, the manufacturer must choose different pad, slurry, and endpoint detectors for metal film and dielectric film to optimize the process. As the technology shrinks to 32 nm and beyond, the standards for the requirements for post CMP uniformity and defect go high. The conventional CMP processes face big challenges to meet these high standards.